Hollow stem poppet valve



June 29, 1954 w. E. AcHoR HoLLow STEM POPPET VALVE Filed May 8, 1951 Patented `une 29, 1954 William E. Achel', "Willoughbyj 'Ohio-,fassignor to Thompsonf Products, Inc;,-Cl'ev'eland, Oliio', a

corporation of Ohio Application'MayS, 1951, Serial No. 225,219

3v Claims. (Cl. 1232-188) 1 This invention relates to a poppet valvestruc-` ture designed for use as an inlet and exhaust Valve for internal combustion engines.

Two'of the most iinportantproblems in valve designV `are concerned with providing suitable means for cooling the valve body to preventwarping and corrosive oxidation of the valve and also' avoiding the formation of coke and varnishes resulting from the high temperature decomposition of fuels and lubricants.

Whilevalves have previously been designed to permitremoval of heat from selected areas of the valve surface, these means usually include a relatively thin-walled stern portion, resulting in the reduction of strength in the valve body,'and thus increasing the possibility of fracture ofthe valve;v

Inthe valve assembly of the present invention I have provided means for controlling the amount of'heat removal from selected areas of the valve, while at the same time providing a sufficiently strong' valve to resist adequately the longitudinal and radial stresses normally occurring in-the` operation of thel valve.

In"theva1ve assembly of the present invention a conventional type cf'poppet valve is provided with an internal cavity for receiving `a coolant, the shape of the cavity being yso arranged as to provide differing amounts of heat removal from selected portions of the valve. The cavity within theintermediate stem portion of the valve is made With a larger diameter than the cavity With' in the upper stem portion of the valve. In one embodiment-of the invention the cavity extends from the `valve.guide-engaging stem portion up into the'headportion of the valve. Contrary to ordinary practice, the head portion is not hollov'vedfout in the valve of the present invention butis provided With only a small diameter cavity, thefdiameter of the cavity in the head being less than thefdiameter in the stem portion. In other Wordsgthe internal cavity of the valve is progressively smaller` .from the. stem portion .of the valverupwardly: into the valve head.

Biff-:providing a varying diametercavity in the;

interior. of the valve assembly, several distinct advantages may be realized.` In the valves .in

the present invention a stronger section resultsv inthe .upper portion of the stem because, rst,`

cavity valves or hollow-headedvalves, thereby" raising' the elastic limitof the valvernaterial at the operating' temperature.

The valves of the fpresent invention' are Aalso designed for the-most advantageous heat removal conditions. 'In hollow-headed valves it is someal times possible to remove'too much neatfro'm the'valve head. Cooling the valve head beyond the point "necessary decreases the vability of the coolingmaterial, suchv as metallic sodium, in the' valve cavity to pick up sufficient heat in the upper-I regions of the valve stem from whichean'adequate amount of heat removable is more critical-y than' it is `in the head portion. The smalldi'-y ameter cavity provided in the head portion `of the'valve of the present invention may extend' any desired distance into thevalve yhead and may be yof such diameter as to remove a suiiicientI amount of heat to effect the proper balancebe-y tween the heat transfer occurring in the headV and stemportions.

The largest diameter of the cavity in the valves1 of this invention occurs in the portion of -the valve stem'which reciprocates Within the valve guide.

Inthis portion of the'valve it is permis-V sible to reduce the strength of the valve to `attain amount of heat transfer. valve in this region is not a particularly critical consideration since lateral thrust or bending is minimizedby the bearing action of the-valve guide# In addition, since the'existing tempera` ture in thev stem portion is relatively 10W due to the heat transfer in this portion,f the yield the present invention has also-the advantage of permitting uniformly controlledflow of heat from the substantially solid valve'head to the coolant cavity'and subsequently tothe valve stem.

It has also been foundthat less coke forma:- tion andvarnish formation occurs on. the'valve stem andvv associated areas of the valve primarily because although more heat is removed from the upper portion of `thevalve stem, considerably less heat is removed from the valve head, and the' total heat transfer to the valve stemis lower thanoccurs when using constant diameter cavities or hollow-headed valves. Consequently, lower temperatures occur in the valve guide andthe lower portions of the lvalve stem, therebyv reducing' theamountof coke and varnish created. by' thahigntemperature.breakdown of hydro.

carbon fuels' and lubricants; Since lower teni,-

3 peratures exist in the valve guide and less coking and varnishing occur, the valve stem wear is reduced.

One of the objects of the present invention is to provide a valve assembly with an internal cavity so arranged as to provide optimum conditions of heat transfer for selected areas of the valve.

Another object of the present invention is to provide a poppet valve structure in which the upper valve stem portion is designed to provide adequate cooling, while still being of suiiicient strength to resist the stresses in this section of the valve.

Another object of the present invention is to provide a valve structure in which the production of coke and varnish formation are minimized by the design of the stem portion of the valve.

A further description of the present invention will be made in connection with the attached sheets of drawings in which:

Figure 1 is a fragmentary View of an engine assembly illustrating the valve of the present invention in its closed position; and

Figure 2 is a view similar to Figure 1 but illustrating the valve in its open position.

As shown on the drawings:

Reference numeral I denotes generally an engine part of an internal combustion engine associated with a combustion chamber in the engine and having a tapered seating face I I against which the poppet valve becomes seated in its closed position. The poppet valve I2 of the present invention consists of a head portion I3 which includes an annular valve seating surface I4 and a flared neck portion I5 joining the head portion I3 to a stem having a stepped bore and a Vclosed tip end. The stern has an upper stem portion I6 extending from the neck I5, an intermediate stem portion I'I which is arranged to reciprocate within a valve guide member I8, and a solid tip or lower end portion I9.

The solid end of the valve stem has a conventional annular retainer lock groove G near the tip thereof for cooperating with a bead 20 of a retainer lock 2l. A conventional valve spring retainer cap 22 is secured on the valve stem by the lock 2 I.

The poppet valve I2 is biased in its closed position, with the valve seating surface I4 in seating relation with the annular seating face Il of the engine part by means of a coiled spring 23 acting between the valve guide member I8 and the valve spring retainer cap 22.

The primary feature of the present invention is concerned with the arrangement of the internal cavities within the poppet valve structure. As shown on the drawing, the intermediate region of the valve stem II is provided with a cavity Ila. of maximum diameter, leaving a thin wall section in the stem portion I'l of the valve. As shown in Figure 2, the larger diameter recess I'Ia extends up the valve stem II a sufficient distance so that the recess Ila, is still within the confines of the valve guide I8 when the valve is in its open portion. Alternately, however, the thin stem wall section enclosing the recess Ila can extend above the guide when the valve is open as long as this section is entirely within the guide when the valve is closed and stressed. In the portion of the valve at the upper stem portion I6 the cavity is reduced in diameter to form a reduced diameter recess IiBa in this area. Through this construction a balance is achieved between the amount of transfer required to cool adequately the upper stem portion I6, while at the same time providing suflicient wall thickness to enable this portion to resist a substantial amount of stress. The cavity I3a in the head portion I1 has the smallest diameter, so that less heat is removed from the head of the valve than is the case where a substantially hollowheaded valve is used.

The cavities of the valve are lled with a coolant material 25 such as metallic sodium, or the like, in the same manner as in ordinary hollow poppet valves of this nature.

While in the drawings I have illustrated an internal cavity having three different dimensions.' it will be appreciated that in some cases, to achieve the proper amount of cooling, the cavity I3a may be of the same diameter as the cavity I6a, or possibly larger. However, in each instance the controlling factor is the construction and size of the cavity associated with the upper stem portion I5 as compared with the cavity in the intermediate stem portion II.

While the various cavities have been illustrated in the drawings as cylindrical in form, it will also be appreciated that the cavities may take various forms, such as a gradual taper from the stem portion to the head portion.

The valve of the present invention may be of a` one-piece construction using material such as SAE 2112 steel. If desired, the stern end of the valve can be composed of a wear-resistant alloy such as SAE 3140 steel. It is also within the scope of the present invention to provide selected areas of the valve body with corrosion-resistant jackets, or sheaths, particularly in the vicinity of the neck portion and the valve seating surface. Typical among such alloys are the Stellite alloys containing 63 to 68% cobalt, 2'7 to 30% chromium, and 2 to 6% tungsten. Suitable corrosion-resistant surfaces can also be welded to the surfaces of the valve body from nickel base alloys having a high degree of corrosion resistance.

It will be understood that modiiications and variations may be effected Without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. An exhaust poppet valve comprising a head portion having a valve seating surface thereon, an intermediate stem portion arranged to reciprocate within a valve guide, an upper stem portion extending from said intermediate stem portion to said head portion, and a solid lower stem portion, said intermediate and upper stem portions having a multi-stepped cavity therein extending from said intermediate stem portion into said head portion said cavity having uniform but diierent sized diameters on opposite sides of the steps, the diameter of said cavity being larger in said intermediate stem portion than in said upper stem portion, and larger in said upper stem portion than in said head portion.

2. A poppet valve comprising a head portion having a valve seating surface thereon, an intermediate stem portion arranged to reciprocate within a valve guide, an upper stem portion extending from said intermediate stem portion to said head portion, and a solid lower stem portion, said intermediate stem portion, said upper stem portion, and said head portion having extending therethrough a continuous multi-stepped cylindrical cavity of at least three different diameters with the largest diameter cavity in said intermediate stem portion, and the smallest diameter cavity in said head portion.

3. A poppet valve for reciprocal mounting in a guide Which terminates in spaced relation from cavity in the upper stem portion and the smallest diameter cavity in said head portion, and said largest diameter cavity remaining in the guide throughout the full reciprocal movement of the a valve port, comprising a head portion having 5 valve.

a valve seating surface thereon for coacting with said port, an intermediate stem portion arranged to reciprocate within a valve guide, an upper stem portion extending from said intermediate stem to said head, said intermediate stem portion, said upper stem portion, and said head portion having extending therethrough a continuous cavity, said cavity consisting of at least three different diameters, said diameters decreasing stepwise with the largest diameter cavity in said intermediate stem, a correspondingly smaller References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Flntermann July 23, 1935 OTHER REFERENCES 15 154 and 155. 

